Google announced Knol, its online user-written encyclopedia project, in December, and now it's open to everyone. The idea is that you can write and own your own page and -- unlike Wikipedia -- no one else can screw it up. Readers can improve it by making suggestions, but it's up to you whether or not you accept them. In that respect it's like, say, Linux, where you can make any improvements you like, but Linus Torvalds can simply ignore them.

Knol is different from Wikipedia in several respects, and an important one is that knolling is a competitive sport. I might write a knol about some aspect of photography, but so might 1,175 other people. There will undoubtedly be a massive duplication of effort, and it's theoretically possible that the cream will rise to the top. But I wouldn't bet on it.

Another thing that's different from Wikipedia is that Knols can make money, and not just for Google. The announcement says:

At the discretion of the author, a knol may include ads from our AdSense program. If an author chooses to include ads, Google will provide the author with a revenue share from the proceeds of those ad placements.

Knols could do quite well, because it looks as though they will get favoured status in Google's search results. The knol on Cardiac Catheterization, Angioplasty and Stenting, for example, is already the top hit for its title, even though precisely zero pages pointed to it until I did. Clearly it is not winning according to its page rank.

There doesn't seem to be any sort of subject index or categorisation, so it might be hard to find a knol if you are looking for one. However, you can use the site: command on Google, like this. And of course, you can search at http://knol.google.com/

Still, if I happened to have written a text book or something similar, I'd probably be converting the popular bits into half a dozen knols for financial and promotional purposes.

I expect the spammers and other chancers are already working away at their knols. Google's Blogger hosts loads of spam blogs, and I don't see anything to stop Knol going the same way.

Whether Knol goes too far in terms of furthering Google's plans for world domination is another matter. If it's successful, it could make life unsupportable for alternative sites with similar ideas. But if it's OK for Google to own Blogger and let you create Web pages etc, why not Knols?